One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10,14,16)(11,17,18,12)(13,15,22,24)(19,23,21,20)(25,26)(27,33)(28,30)(29,32)(31,35)(34,39)(36,37)(38,40)(1,2)(3,5)(4,6)(7,8)(9,11)(10,12)(13,21)(14,18)(15,23)(16,17)(19,22)(20,24)(25,26,30,28)(27,31,35,33)(29,36,37,32)(34,39,40,38)(11,18)(12,17)(19,21)(20,23)(26,28)(31,33)(32,36)(38,39) involution — undirected(9,11)(10,12)(13,19)(14,18)(15,20)(16,17)(21,22)(23,24)(25,27,30,35)(26,31,28,33)(29,34,37,40)(32,38,36,39)(9,12)(10,11)(13,20)(14,17)(15,19)(16,18)(21,24)(22,23)(25,28,30,26)(27,33,35,31)(29,36,37,32)(34,39,40,38)(1,3,4,7)(2,5,6,8)(9,13,14,22)(10,15,16,24)(11,19,18,21)(12,20,17,23)(25,29,30,37)(26,32,28,36)(27,34,35,40)(31,38,33,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.